Coating applicator



2 Sheets-Sheet 1 N2 53 NNINVENTOR. CV/F/brd ecor QWI W A TTURNEYS Nov.15, 1966 c. R. RECOR COATING APPLICATOR Filed May 2, 1963 Nov. 15, 1966c. R. RECOR 3,285,225

COATING APPLI CATOR Filed May 2, 1965 2 Sheets-Sheet 2 mill INVFNTOR.

United States Patent 3,285,225 COATING APPLICATOR Clifford R. Recor,Beloit, Wis., assignor t0 Beloit Corporation, Beloit, Wis., acorporation of Wisconsin Filed May 2, 1963, Ser. No. 277,627 4 Claims.(Cl. 118410) This invention relates to improvements in coating porouswebs such as webs of paper or the like, and more particularly, to animproved apparatus for applying coatings topaper webs.

The instant invention is directed to a coating apparatus for obtaining ahighly uniform deposit of a coating formulation onto a surface of atrevaling web. Although the apparatus is applicable to traveling webs ofpaper, plastic, cloth, metal sheets. etc., the invention will bedescribed primarily in connection wtih paper webs. Modern coatingpractice involves relatively high speeds of travel for the web and arelatively limited area in which the coating is to be applied to the weband metered or smoothed onto the web in the desired weight anduniformity. The weight at which coatings are applied to webs isgenerally expressed by those skilled in the art in terms of pounds perunit of area, such as pounds perpaper ream. The coating compositions assuch are generally referred to in the art on the basis of their solidscontent, which characterizes the coating compositions to the extentnecessary for the skilled worker in the art. The instant inventionaffords an apparatus for the application of relatively high coatingweights at comparatively high operating speeds (generally expressed infeet per minute of longitudinal travel of the web), in such a manner asto obtain superior uniformity of application and penetration of the websurface by the coating composition.

It is, therefore, an important object of the instant invention toprovide an improved coating apparatus.

It is a further object of the instant invention to provide an improvedcoating apparatus for obtaining superior uniformity of application ofthe coating, superior penetration of the coating composition intosurface portions of the web, improved coating speeds and improvedcoating finish on the web.

Other and further objects, features and advantages of v the presentinvention will become apparent to those skilled in the art from thefollowing detailed disclosure thereof and the drawings attached heretoand made a part hereof.

On the drawings:

FIGURE 1 is a fragmentary side elevational view showing essentialelements of the coating device of the invention;

FIGURE 2 is a fragmentary top plan view of the coating chamber of theinvention shown in FIGURE 1 taken substantially along the line 11-11 ofFIGURE 1 with certain parts including the upper roll removed;

FIGURE 3 is a sectional elevational view taken substantially along theline IIIIII of FIGURE 2;

FIGURE 4 is a detail sectional elevational view taken substantiallyalong the line IVIV of FIGURE 3; and

FIGURE 5 is a diagrammatic elevational view of the overall assembly ofthe instant coating device.

As shown on the drawings:

The coating device indicated generally at in FIG- URES 1 and 5 hereof isa coating device for a web W traveling longitudinally (in the directionindicated by the arrows) over a transverse supporting device, which ispreferably a supporting roll 11 rotatable about a transverse axis 11aand substantially transversely coextensive along its peripheral surfacewith the web W. In the instant specification and claims the direction ofthe web travel is referred to as the longitudinal direction and thecross machine direction or the direction of the width of the wab isreferred to generally as the transverse direction. Reference to elementsat the oncoming side of a given location refers to the oncoming side inthe longitudinal direction and reference to elements at the off-runningside of a given location refers to the off-running side in thelnogitudinal direction of the web travel.

From FIGURE 5, it will be seen that the web W travels around therotating roll 11 and is firmly supported on the surface thereof as itpasses a coating device indicated generally by the reference numeral 12.At the off-running side of the coating device 12 a trailing blade 13 ispreferably mounted in conventional manner for the purpose of smoothingthe coating carried on the web W. In general the coating device 12applies a predetermined amount of coating to the web W and the trailingblade 13 is employed primarily for smoothing purposes, although it willbe appreciated that the trailing blade 13 might be employed for removalof excess coating, if it is desired to apply excess coating to the webvia the instant coating device 12, and in such instance excess coatingmight be returned to the coating pan indicated at 14 in FIGURE 5 and inFIGURE 1.

Referring to FIGURES 1 and 4, it will be seen that the coating device 12comprises a shallow open topped coating chamber indicated at C in FIGURE1 defined between the web covered roll 11 and an arcuately contouredbottom wall or floor 21 having substantially the contour of theperiphery of the roll 11. In fact, in the instant device the radius forthe roll 11 is substantially 16 inches and the radius of the arcuatecontour of the chamber floor 21 is substantially inch greater.

As indicated in FIGURE 4, the chamber is provided with side walls, oneof which is shown at 21a (and the other of which is shown at 21b inFIGURE 1) for close running operation with the sides of the roll 11. Inaddition, the floor 21 of the chamber C is provided with a generallytransverse oncoming edge 21c which receives the web W traveling on theroll 11 and is positioned in sufficiently close running relation theretoto effectively assist in the retention of compressive forces on thecoating in the chamber C which is in the form of a film indicated at Fin full view in FIGURE 4. The web W is also indicated in full view, butshown only partially in FIG- URE 4 to avoid obscuring the position ofthe other elements. The chamber floor 21 is also provided with anoff-running transverse edge 21d and this off-running edge 21d may itselffunction as a dam for metering the coating layer carried away from thechamber C on the web W. If desired, a blade or knife 22 may be adaptedby suitable means such as bolts 23 along the off-running edge 21d tofunction as a coating metering device or dam. The web W backed by theroll 11 is driven through the chamber C and against the coating film Funder substantial compressive forces, which are of course increased bythe hydraulic wedge effect that is obtained as the roll drives the webagainst the film with decreasing radial clearance in the direction ofthe off-running chamber edge 21d.

It will thus be appreciated that the shallow coating chamber C isprovided w th a first surface portion 21c co-nforming generally with theroll 11 toward the oncoming edge 21c and defining a narrow transverseslot with the roll 11 to receive the web W at the oncoming side. Thechamber floor 21 also has a second surface portion 21 conforminggenerally with the roll 11 toward the off-running edge 21d defining ametering slot for the coating on the web passing therethrough, eitherwith the off-running edge 21d or with the additional knife edge 22. Asis indicated in dotted lines in FIGURE 1, the off-running floor portion21] converges with the roll 11 carrying the web W thereon toward thetrailing edge 21d.

Referring again to FIGURE 4, however, it will be seen that the oncomingand'off-runing edges 21c and 21d are coplanar, lying in the plane P-1and the floor portions 21e and '21 of the chamber converge toward theseedges, respectively, in defining the contour of the bottom of thechamber C.

' Coating is, of course, removed from the chamber C on the web W pastthe trailing edge 21d or the dam 22 and additional coating must be adedto the film F during the operation. This is done via a multiplicity ofsmall generally transversely spaced passageways 25, 25, etc. which areaimed at the web W, generally perpendicularly thereto and in generalradial alignment with the roll 11 itself, so that coating may be addedunder pressure directly against the web surface for obtaining thedesired penetration of coating into the web surface. A relatively largetransversely extending passageway 26 is mounted directly beneath theradial passages 25 for feeding coating under pressure upwardly into thepassages 25. The transverse passageway 26 is fed by coating underpressure from a suitable source indicated diagrammatically at S in FIG-URE 1 into side entrances 27 at one or both ends of the transversepassageway 26 and the coating under high pressure passes through therelatively restricted lower ends 25a of the radial passages 25. Therestricted passages 25a are employed for ease of maintenance of asubstantially uniform pressure across the entire width of the transversepassageway 26, so that the flow of coating upwardly through each of thegenerally radially aligned passages 25 will be substantially uniform.The pressures generated in the chamber C, however, are quite substantialso the chamber floor wall 21g is of substantial thickness and theradially aligned passages are of substantial length beyond the narrowrestricted entrances 25a, and the passages 25 are flared or opened attheir mouths 25b. It will be appreciated that the floor portion 21g forthe chamber C is formed of two mating elements shown in FIGURE 4 as abottom element 21k seating a nested upper element 21 so that thecomplete radial passage 25 shown in FIGURE 4 is apparent. Actually, eachpassage 25 extends upwardly from the restricted bottom 25a to a firstenlargement 250 in the element 21k, then to a second enlargement 25dfeeding into a [laterally aligned shallow pressure equalizing slot 26ainterconnecting the passages 25 (and shown in top plan lview in FIGURE2), and then (referring back to FIGURE 4) the second enlargement 25d hasa radial extension 256 in the upper element 21 which feeds to the flaredopening 25b. In FIGURES 2 and 3, the upper nested element 21 is removedfor simplification of the showing in the drawings. The upper nestedelement 21 is, of course, secured to the lower element 21k to form thecomposite floor 21g by suitable means such as bolts (e.g. at 21x) or thelike.

Referring also to FIGURES 2 and 3, it will be seen that edge coatinglines 30, 30 feed into a slot 31 aligned substantially with the edge ofthe web along the upper faceof the chamber, and a water seal slot 32 isprovided immediately outside of the coating slot 31 and connectedthrough a suitable passageway 33 to water under pressure for effectingthe desired seal and to and drying at the ends or edges.

Referring also to FIGURE 1, it will be noted that an upright framesupported on the floor indicated at 41 carries a pivot 42 which swings amounting arm 43 carrying a frame element 44 with a pivot pin 45 therein.The pivot pin 45 carries a generally horizontal frame element 46 thatsupports the coating chamber structure indicated generally at 12 andmounts the same for limited tilting movement about the pivot 45 which isadjacent the oncoming edge 21c. A set screw and lock nut as sembly 47 ismounted beneath the horizontal frame 46 for adjustably tilting the frame46 and thereby adjusting the clearance between the roll 11 land thechamber trailing edge 21d (and the end dam 22, whichever is used todetermine the final clearance in the operation of the coating device).

The coating pan 14 previously mentioned is also carried preventcoagulation in conventional manner on the swinging arm 43; which ismounted for pivotal movement about the transverse axis for the pivot 42.The transverse axis for the pivot 42 is spaced substantially from thetransverse axis for the pivot 45 and afford swinging movement for thearm 43 in and out of operating position and also into operating positionby virtue of the fluid motor 48 which is a conventional pneumaticcylinder resiliently urging the chamber C, with the coating film Ftherein, against the web W on the roll 11.

A specific example of a coating composition used in the practice of theinstant invention has the following formulation (with all parts given byweight as is conventional):

7 Parts Clay Titanium dioxide 10 Casein 4 Latex adhesive (Dow Latex512L-Solid Spaces) 12 Ammonium hydroxide (28%) 0.6 Ammonium stearate 2Water 156 The above formulation has a solids content of about 43% and aviscosity of approximately 550 centipoises, although viscosities withinthe range of about to about 1500 centipoises can be used convenientlyherein and viscosities of as much as 30,000 centipoises can be used withadequate pumping means for forcing the coating into the location of thefilm F. This permits the use of coatings from a minimum practical solidsproportion of about 30% to a maximum practical solids proportion ofabout 65%. The foregoing 43% solids coating is applied in the practiceof the instant invention maintaining about 10 pounds per square inch onthe film F for the application of coating weight of about 7 pounds perream at an operating speed of 1000 feet per minute. Coating weights inthe range of 5 to 30 pounds per ream may be employed in the practice ofthe instant invention at speeds ofsubstantially 300 to 2500 feet perminute.

It'will be understood that modifications and variations may be effectedwith-out departing from the spirit and scope of the novel concepts ofthe present invention.

I claim as my invention:

1. .A coating device for a web travelling longitudinally, comprising arotary support roll substantially transversely coextensive with andmoving with the web supported thereby, means defining a shallow coatingchamber spaced from said roll and having a first surface portionconforming generally with said roll toward an on-coming edge defininganarrow transverse slot with the roll to receive the web at theon-coming side and having a second surface portion conforming generallywith said roll toward an offrunning edge defining a narrow transverseslot for meter-- ing coating onto the web passing therethrough, andmeans defining a multiplicity of passageways in said chamberintermediate said surface portions aimed toward said roll for urgingcoating under pressure against the web on the roll, and means fortilting said chamber about a transverse axis for selectively moving saidoff-running edge toward and away from said roll to control metering ofthe coating and means for swinging said transverse axis about a secondtransverse axis remote from the roll surface for selectively moving saidchamber toward and away from said roll to control pressure loading ofthe coating against the web on the roll.

2. A coating device for a web travelling longitudinally, com-prlsing arotary support roll substantially transversely coextensive with 'andmoving with the web supported thereby, means defining a shallow coatingchamber spaced from said roll and having a first surface portionconformmg generally with said roll toward an on-coming edge defining anarrow transverse slot with the roll to receive the web at the on-comingside and having a second surfaceportion conforming generally with saidroll toward an off-running edge defining a narrow transverse slot formetering coating onto the web passing therethrough, means defining amultiplicity of passageways in said chamber intermediate said surfaceportions aimed toward said roll for urging coating under pressureagainst the web on the roll, means for tilting said chamber about atransverse axis for selectively moving said off-running edge toward andaway from said roll to control metering of the coating, and fluidpressure actuated arms swinging said chamber about a second transverseaxis remote from the roll surface for selectively moving said chambertoward and away from said roll to control pressure loading of thecoating against the web on the roll.

3. A device adapted to apply coating to a web travelling longitudinallyover a transverse suppotrt, comprising means defining a shallowopen-topped chamber between longitudinaly spaced transverse co-plana-redges and having opposed transverse surface portions converging upwardlyfrom a bottom portion with the plane of said edges respectively towardeach of said edges, means defining a multiplicity of passagewaystransversely spaced along said bottom and aimed at said plane, meansdefining a transverse passageway adapted to feed coating under pressureinto said chamber through said multiplicity of passageways, means fortilting said chamber about a first transverse axis adjacent said edges,and fluid pressure actuated resilient means for swinging said chamberabout a second transverse axis spaced from the first axis.

4. A coating device for a web travelling longitudinally, comprising arotary support roll substantially transversely coextensive with andmoving with the web supported thereby, means defining a shallowopen-topped chamber between longitudinally spaced transverse coplanaredges in close running relation to said roll and having opposedtransverse surface portions converging upwardly from a bottom positionwith the plane of said edges respectively toward each of said edges,means defining a multiplicity of passageways transversely spaced alongsaid bottom and aimed at said plane, means defining a transversepassageway adapted to feed coating under pressure into said chamberthrough said'multiplicity of passageways, means for tilting said chamberabout a first transverse axis adjacent said edges, and fluid pressureactuated resilient means for swinging said chamber about a secondtransverse axis spaced from the first axis.

References Cited by the Examiner UNITED STATES PATENTS 2,190,809 2/ 1940Strauch 118-413 2,243,333 5/1941 Diescher 118-410 2,349,256 5/ 1944Evans 118-411 2,464,771 3/ 1949 Van Guelpen 118-413 X 2,937,955 5/ 1960Loomer 117-111 X 3,029,780 4/1962 Justus et al 117-126 3,063,868 11/1962Brandsma et al. 117-120 X 3,079,889 3/1963 Jacobs et al 118-413 X3,097,107 7/ 1963 Martinek 117-111 X ALFRED L. LEAVITT, PrimaryExaminer.

JOSEPH B. SPENCER Examiner.

I. M. BATTEN, 111., Assistant Examiner.

1. A COATING DEVICE FOR A WEB TRAVELING LONGITUDINALLY, COMPRISING AROTARY SUPPORT ROLL SUBSTANTIALLY TRANSVERSELY COEXTENSIVE WITH ANDMOVING WITH THE WEB SUPPORTED THEREBY, MEANS DEFINING A SHALLOW COATINGCHAMBER SPACED FROM SAID ROLL AND HAVING A FIRST SURFACE PORTIONCONFORMING GENERALLY WITH SAID ROLL TOWARD AN ON-COMING EDGE DEFINING ANARROW TRANSVERSE SLOT WITH THE ROLL TO RECEIVE THE WEB AT THE ON-COMINGSIDE AND HAVING A SECOND SURFACE PORTION CONFORMING GENERALLY WITH SAIDROLL TOWARD AN OFFRUNNING EDGE DEFINING A NARROW TRANSVERSE SLOT FORMETERING COATING ONTO THE WEB PASSING THERETHROUGH, AND MEANS DEFINING AMULTIPLICITY OF PASSAGEWAYS IN SAID CHAMBER INTERMEDIATE SAID SURFACE,PORTIONS AIMED TOWARD SAID ROLL FOR URGING COATNG UNDER PRESSURE AGAINSTTHE WEB ON THE ROLL, AND MEANS FOR TILTING SAID CHAMBER ABOUT ATRANSVERSE AXIS FOR SELECTIVELY MOVING SAID OFF-RUNNING EDGE TOWARD ANDAWAY FROM SAID ROLL TO CONTROL METERING OF THE COATING AND MEANS FORSWINGING SAID TRANSVERSE AXIS ABOUT A SECOND TRANSVERSE AXIS REMOTE FROMTHE ROLL SURFACE FOR SELECTIVELY MOVING SAID CHAMBER TOWARD AND AWAYFROM SAID ROLL TO CONTROL PRESSURE LOADING OF THE COATING AGAINST THEWEB ON THE ROLL.